My macbook pro 10.6.8 Mail stopped working. I can't receive from IMAP ISP or iCloud acct

on 10-29 my macbookpro 10.6.8 stopped receiving mail from my ISP and from my MobileMe (iCloud account). I got repeated pop-ups for my password at the ISP. So at the Spokane genius bar, Frank re-loaded the accounts in mail and they seemed to work. But I just signed up for a site and they sent me a verification e-mail. I have not received it, and now I'm not even receiving my test mails. Where are they going?